Low density pet litters and methods of making such pet litters

ABSTRACT

Compacting expanded perlite fines in the presence of a small amount of binder (starch and/or clay) and water, followed by drying, produces particles with low density, good integrity, and surprisingly higher absorption by volume than non-compacted expanded perlite or non-swelling clay. Furthermore, addition of a small amount of clumping agent (e.g., guar gum) to the compacted granules results in a clumping litter with low density, good integrity and comparable clumping ability to traditional clay clumping litter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/245,349 filed Oct. 23, 2015, the disclosure of which is incorporatedby references in its entirety.

BACKGROUND

The present disclosure relates generally to a low density absorbentmaterial which can be used in both clumping and non-clumping pet litter.More specifically, the present disclosure is directed to low density petlitters comprising compacted particles of expanded perlite and methodsfor making and using such pet litters

Litter boxes are used by pets such as cats for elimination of urine andfecal matter. A litter box contains a layer of pet litter that receivesthe urine and fecal matter. The pet litter is granular, absorbent andeither non-clumping or clumping. A clumping pet litter is a litterproduct in which the particles facilitate formation of clumps after theurine and fecal matter is deposited in the pet litter. The clumps aretypically sifted from the litter box using a litter scoop and thendiscarded. Non-clumping pet litter is typically better at absorbingurine and thus removing urine odors, but replacing soiled non-clumpingpet litter without emptying the entire box of litter can be difficult.

Consumers fill their litter boxes based on volume, so litters should behighly absorbent by volume. However, traditional absorbent litters arebulky and dense, and thus packages of such litters are heavy anddifficult to handle.

Existing litters include compositions made from clay minerals, silicagel, and agricultural wastes. Clay minerals are absorptive but alsoheavy. Silica gel is also absorptive, but the commonly used aggregateshape and size can have poor cat acceptance, which can lead to housesoiling and/or a risk of urinary minerals aggregating into stones orcrystallizing in a cat. Agricultural wastes are also absorptive, butmany are in pellet form and can have poor animal acceptance.Agricultural waste litters, due to their composition, may also serve asfood source and thus support growth of odor causing microorganisms inthe litter box.

U.S. Pat. No. 5,655,480 to Steckel et al. discloses an animal controllitter comprised of a clumping agent, a surfactant, an odor controlagent and light weight aggregate expanded to form porous surfaces bysubjecting the aggregate to a temperature of 1,800° F. This litter has adensity between 5 and 10 lb/ft³. However, the material is lessabsorptive by volume than clay. Additionally, the expanded perliteaggregate material is fragile and can break down easily. The materialmay also be “too light” for good cat acceptance.

SUMMARY

The present disclosure relates to low density pet litters comprisingcompacted particles of expanded perlite, preferably having a diametersmaller than 30 mesh (that is, a diameter smaller than 595 microns) andpreferably as the primary ingredient in the litter. As a non-limitingexample, about 95% or more of the perlite fines in the compactedparticles can have a diameter smaller than 30 mesh (that is, a diametersmaller than 595 microns) and no greater than about 5% of the compactedparticles can be up to 4 mesh (that is, have a diameter greater than4.76 mm).

The present inventors unexpectedly found that compacting expandedperlite fines in the presence of a small amount of starch and water,followed by drying, produces particles with low density, good integrity,and surprisingly higher absorption by volume than non-compacted expandedperlite or non-swelling clay. Furthermore, addition of a small amount ofclumping agent (e.g., guar gum) to the compacted granules results in aclumping litter with low density, good integrity and comparable clumpingability to traditional clay clumping litter.

Accordingly, in a general embodiment, the present disclosure provides amethod of making a pet litter. The method comprises: compacting amaterial comprising expanded perlite fines to form a compacted materialcomprising expanded perlite; breaking the compacted material comprisingexpanded perlite to form particles of the compacted material comprisingexpanded perlite; separating the particles which have a size within apredetermined size range from a remainder of the particles; drying theparticles which have the size within the predetermined size range; andusing the dried particles as at least a portion of the pet litter. Inanother embodiment, the present disclosure provides a pet litter made bythis method.

In an embodiment, the expanded perlite fines have a size not greaterthan about 600 microns. In one embodiment, the expanded perlite fineshave a diameter from about 50 microns to about 600 microns,alternatively from about 100 microns to about 550 microns, alternativelyfrom about 150 microns to about 500 microns, alternatively from about200 microns to about 450 microns, alternatively from about 250 micronsto about 400 microns, alternatively from about 300 microns to about 350microns.

In one embodiment, the breaking of the compacted material comprisingexpanded perlite fines and/or drying are optional.

In an embodiment, the compacting is performed at a pressure from about500 psi (3447 kPa) to about 1,300 psi (8963.18 kPa).

In an embodiment, the material comprises about 0.25 wt % to about 5.0 wt% of a binder. The binder can be starch (e.g., pre-gelled cereal starch)and/or clay. At least a portion of the binder can be added to theexpanded perlite fines as a dry mix before the compacting of thematerial. At least a portion of the binder can be pre-blended with waterand then added to the expanded perlite fines before the compacting ofthe material.

In an embodiment, the water in the material comprises about 15.0 wt % toabout 25.0 wt % of water.

In an embodiment, the material comprises about 50 wt % to about 85 wt %of the expanded perlite fines.

In an embodiment, the predetermined size range is about 595 microns toabout 2,380 microns.

In an embodiment, the particles are dried to a moisture content of about0.25 wt % to about 10.0 wt %.

In another embodiment, the present disclosure provides a pet littercomprising dried particles of compacted material comprising expandedperlite, the particles having a density of about 25.0 lb/ft³ to about45.0 lb/ft³, preferably about 30.0 lb/ft³ to about 42.0 lb/ft³.

In an embodiment, the litter is a non-clumping litter that does notcontain a clumping agent.

In an embodiment, the litter is a clumping litter comprising a clumpingagent. The clumping agent can be selected from the group consisting ofbentonite, guar gum, starches, xanthan gum, gum Arabic, gum acacia,silica gel, and mixtures thereof.

In an embodiment, the pet litter further comprises an additive selectedfrom the group consisting of an odor control agent, a fragrance, ananti-microbial agent, an anti-sticking agent, an agent for controllingpH, a dye, a coloring agent, a de-dusting agent, a disinfectant, andcombinations thereof. An odor control agent can be carbon, particularlyactivated carbon.

In another embodiment, the present disclosure provides a method ofmanaging animal waste. The method comprises using pet litter comprisingdried particles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 45.0 lb/ft³(preferably about 30.0 lb/ft³ to about 42.0 lb/ft³) in a litter box.

In another embodiment, the present disclosure provides a method oftreating out-of-box elimination of a pet. The method comprises using petlitter comprising dried particles of compacted material comprisingexpanded perlite, the particles having a density of about 25.0 lb/ft³ toabout 45.0 lb/ft³ (preferably about 30.0 lb/ft³ to about 42.0 lb/ft³) ina litter box located in a building in which the pet resides.

In another embodiment, the present disclosure provides a method oftreating, preventing or reducing the risk of a lower urinary tractdisease in a cat. The method comprises using pet litter comprising driedparticles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 45.0 lb/ft³(preferably about 30.0 lb/ft³ to about 42.0 lb/ft³) in a litter boxlocated in a building in which the cat resides.

An advantage of one or more embodiments provided by the presentdisclosure is to provide improved pet litters.

Another advantage of the present disclosure is to provide methods ofmaking improved pet litters.

A further advantage of the present disclosure is to provide pet littersthat have a low density without sacrificing particle integrity orabsorptive performance.

Still another advantage of the present disclosure is to provide petlitters that have both a low density and good pet acceptance.

Yet another advantage of the present disclosure is to enable lighterpackages of pet litter without decreasing the volume thereof.

Another advantage of the present disclosure is to enable a pet owner tomore easily purchase, transport and utilize a package of pet litter.

A further advantage of the present disclosure is to provide a lowdensity granular absorbent with good particle integrity and havingsurprisingly improved absorption relative to traditional clay litter andthe pre-processed principal raw material.

Still another advantage of the present disclosure is to provide amaterial that can be used as an improved non-clumping pet litter oremployed in a formulation for an improved clumping pet litter.

Additional features and advantages are described herein and will beapparent from the following Detailed Description.

DETAILED DESCRIPTION

As used in this disclosure and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a material” or “thematerial” includes two or more materials.

The words “comprise,” “comprises” and “comprising” are to be interpretedinclusively rather than exclusively. Likewise, the terms “include,”“including” and “or” should all be construed to be inclusive, unlesssuch a construction is clearly prohibited from the context.

However, the devices and compositions disclosed herein may lack anyelement that is not specifically disclosed. Thus, a disclosure of anembodiment using the term “comprising” includes a disclosure ofembodiments “consisting essentially of” and “consisting of” thecomponents identified. Similarly, the methods disclosed herein may lackany step that is not specifically disclosed herein. Thus, a disclosureof an embodiment using the term “comprising” includes a disclosure ofembodiments “consisting essentially of” and “consisting of” the stepsidentified. “Consisting essentially of” means that the embodimentcomprises more than 50% of the identified components, preferably atleast 75% of the identified components, more preferably at least 85% ofthe identified components, most preferably at least 95% of theidentified components, for example at least 99% of the identifiedcomponents.

The term “and/or” used in the context of “X and/or Y” should beinterpreted as “X,” or “Y,” or “X and Y.” Where used herein, the terms“example” and “such as,” particularly when followed by a listing ofterms, are merely exemplary and illustrative and should not be deemed tobe exclusive or comprehensive. Any embodiment disclosed herein can becombined with any other embodiment disclosed herein unless explicitlystated otherwise.

All percentages expressed herein are by weight of the total weight ofthe composition unless expressed otherwise. As used herein, “about” and“approximately” are understood to refer to numbers in a range ofnumerals, for example the range of −10% to +10% of the referencednumber, preferably within −5% to +5% of the referenced number, morepreferably within −1% to +1% of the referenced number, most preferablywithin −0.1% to +0.1% of the referenced number. All numerical rangesherein should be understood to include all integers, whole or fractions,within the range. Moreover, these numerical ranges should be construedas providing support for a claim directed to any number or subset ofnumbers in that range. For example, a disclosure of from 1 to 10 shouldbe construed as supporting a range of from 1 to 8, from 3 to 7, from 1to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth.

Numerical adjectives, such as “first” and “second,” are merely used todistinguish components. These numerical adjectives do not imply thepresence of other components, a relative positioning, or anychronological implementation. In this regard, the presence of a “secondwidget” does not imply that a “first widget” is necessarily present.Further in this regard, a “second widget” can be used before, after, orsimultaneously with any “first widget.”

The terms “pet” and “animal” are used synonymously herein and mean anyanimal which can use a litter box, non-limiting examples of whichinclude a cat, a dog, a rat, a ferret, a hamster, a rabbit, an iguana, apig or a bird. The pet can be any suitable animal, and the presentdisclosure is not limited to a specific pet animal. The term“elimination” means urination and/or defecation by a pet.

As used herein, the term “litter” means any substance that can absorbanimal urine and/or decrease odor from animal urine and/or feces. A“clumping litter” forms aggregates in the presence of moisture, theaggregates distinct from the other litter in the litter box. A“non-clumping litter” does not form distinct aggregates.

The term “litter box” means any apparatus that can hold pet litter, forexample a container with a bottom wall and one or more side walls,and/or any apparatus configured for litter to be positioned thereon, forexample a mat or a grate. As a non-limiting example, a litter box may bea rectangular box having side walls that have a height of at least aboutsix inches.

The term “mesh” is defined by the ASTM E-11 U.S.A. standardspecification for sieves. As used herein, “size” of a particle refers tothe length of the longest dimension of the particle.

The methods and devices and other advances disclosed herein are notlimited to particular methodologies, protocols, and reagents because, asthe skilled artisan will appreciate, they may vary. Further, theterminology used herein is for the purpose of describing particularembodiments only and does not limit the scope of that which is disclosedor claimed.

Unless defined otherwise, all technical and scientific terms, terms ofart, and acronyms used herein have the meanings commonly understood byone of ordinary skill in the art in the field(s) of the presentdisclosure or in the field(s) where the term is used. Although anycompositions, methods, articles of manufacture, or other means ormaterials similar or equivalent to those described herein can be used,the preferred devices, methods, articles of manufacture, or other meansor materials are described herein.

An aspect of the present disclosure is a method of making a pet litter.The method can comprise compacting a material comprising expandedperlite fines, a binder and water, for example using compacting rolls.

The compacting can be performed at a compaction roll back-pressure of atleast about 500 psi (3447 kPa), for example about 500 psi (3447 kPa) toabout 1,300 psi (8963.18 kPa), such as about 500 psi (3447 kPa) to about800 psi (5516 kPa) or about 800 psi (5516 kPa) to about 1,300 psi(8963.18 kPa). The size of the expanded perlite fines is preferably notgreater than about 30 mesh (that is, having a diameter not greater than595 microns). As a non-limiting example, about 95% or more of theperlite fines in the compacted particles can be smaller than 30 mesh(that is, having a diameter smaller than 595 microns) and no greaterthan about 5% of the compacted particles can be up to 4 mesh (that is,having a diameter greater than 4.76 mm). In an embodiment, the expandedperlite fines comprise particles eliminated in step 101 of the method100 disclosed in U.S. Patent App. Pub. No. 2014/0174370 to Huck et al.,herein incorporated by reference in its entirety.

The present disclosure is not limited to a specific means of forming thecompacted particles, and other means of compaction or agglomeration ofthe perlite fines can be employed additionally or alternatively tocompacting rolls. These other means include, for example, tumble/growthagglomeration; low-, medium-, or high pressure agglomeration; punch anddie; roller press; high shear mixer granulator; extrusion; andcombinations thereof.

Perlite is a generic term for a naturally occurring siliceous rock. Onefeature which sets perlite apart from other volcanic glasses is thatwhen heated to a suitable point in its softening range, perlite expandsfrom four to twenty times the original volume. This expansion is due, atleast in part, to the presence of two to six percent combined water inthe crude perlite rock. Firing, i.e., quickly heating to above 1,600° F.(871° C.), causes the crude rock to pop in a manner similar to popcornyielding a very open, highly porous structure referred to as expandedperlite.

In an embodiment, the amount of expanded perlite fines is about 50 wt %to about 85 wt % of the material, for example about 70 wt % to about 80wt %, preferably about 75 wt % of the material. In an embodiment, theamount of the water is about 15 wt % to about 25 wt % of the material,for example about 20 wt % of the material.

In an embodiment, the amount of the binder is about 0.25 wt % to about5.0 wt % of the material, for example about 1.0 wt % to about 4.0 wt %,preferably about 3.0 wt % to about 3.5 wt % of the material. The bindercan be starch and/or clay. Preferably, the starch (if any) comprises acereal starch, for example starch from one or more of rice, millet,wheat, corn or oats. In a preferred embodiment, the starch (if any)comprises pre-gelled cereal starch and can include any waxy or highamylose varieties thereof. The clay can be swelling or non-swelling.Preferably, the clay (if any) comprises one or more clay mineralsselected from the group consisting of kaolin, smectite, illite,chlorite, sepiolite, and atapulgite. In a preferred embodiment, the clay(if any) comprises a montmorillonite smectite and most preferably sodiumor calcium montmorillonite.

At least a portion of the binder can be added to the expanded perlitefines as a dry mix before the compacting. Alternatively or additionally,at least a portion of the binder can be pre-blended with at least aportion of the water and then added to the expanded perlite fines beforethe compacting.

In an embodiment, the compacting forms a compacted material such assheets and/or briquettes of compacted expanded perlite fines. However,the compacted material is not limited to a specific shape, size or form.Furthermore, as noted above, the present disclosure is not limited to aspecific means of compaction or agglomeration of the perlite fines toform the compacted material. For example, the compacted material can bein the form of a pellet (e.g., a flattened pellet), a tablet or a puck.

Then the compacted material can be ground and/or crushed, for example bya milling system or any other suitable apparatus known to one skilled inthe art, to obtain particles of compacted material comprising expandedperlite. One or more sieves can be used to obtain the particles ofcompacted material comprising expanded perlite that have a desired sizeby separating the particles having the desired size from the remainderof the particles. The desired particle size is preferably from about 30mesh (595 microns) to about 8 mesh (2,380 microns). Preferably, theparticles of compacted material comprising expanded perlite are notevenly distributed within the size range. Commercially available shakerscreens may be utilized.

The particles of compacted material comprising expanded perlite thathave the desired size can be subjected to drying to remove moisture fromthe particles without substantially damaging the particles. For example,the particles can be transferred to a dryer such as a fluidized beddryer. The resultant moisture level can be about 0.25% to about 10%, forexample about 2%.

The dried particles of compacted material comprising expanded perlitepreferably have a density of about 25 lb/ft³ to about 45 lb/ft³, morepreferably about 30 lb/ft³ to about 42 lb/ft³.

In some embodiments, the dried particles of compacted materialcomprising expanded perlite are combined with a clumping agent; i.e., anagent that binds adjacent particles when wetted. The combination of thedried particles with the clumping agent can be performed in a mixer andcan form at least a portion of a clumping pet litter. The clumpinglitter preferably comprises the dried compacted particles and theclumping agent in a ratio from 99:1 to 94:6, for example about 96:4.Non-limiting examples of suitable clumping agents include bentonite(such as sodium bentonite), guar gum, starches, xanthan gum, gum Arabic,gum acacia, silica gel, other minerals, and mixtures thereof. Apreferred embodiment of the clumping agent comprises guar gum.Nevertheless, in an embodiment, starch is used in the binder andadditional starch is used in the clumping agent, although the starchused in the binder is added to the expanded perlite fines before and/orduring compacting, and the starch used in the clumping agent is added tothe particles of compacted perlite, preferably after drying.

In other embodiments, the dried particles of compacted materialcomprising expanded perlite are not coated with a clumping agent, andthe dried particles of compacted material comprising expanded perliteform at least a portion of a non-clumping litter. In such embodiments,the dried particles can be packaged directly after the drying withoutfurther processing.

Various additives may be optionally applied to the dried compactedparticles. Non-limiting examples of suitable additives include an odorcontrol agent, a fragrance, an anti-microbial agent, an anti-stickingagent, an agent for controlling pH, a dye, a coloring agent, ade-dusting agent, a disinfectant, and combinations thereof. In anembodiment, at least a portion of the dried compacted particles arecoated with a colorant.

For embodiments in which the pet litter is a non-clumping litter, theadditives can be applied to the dried compacted particles directly afterthe drying, to form the non-clumping litter, without further processing.Then the non-clumping litter can be packaged directly after theapplication of the additives, without further processing.

For embodiments in which the pet litter is a clumping litter, theadditives and the clumping agent, together or separately, can becombined with the dried compacted particles directly after the drying,to form the clumping litter, without further processing. Then theclumping litter can be packaged directly after the combination, withoutfurther processing.

In a preferred embodiment, the pet litter does not contain clay. In apreferred embodiment, the pet litter does not contain agriculturalproducts, such as alfalfa, corn, corn stalk, corn flour, oat hull, oatstalk, oat flour, barley hull, barley meal, barley stalk, barley flour,wheat hull, wheat straw, wheat flour, soybean hull, soybean meal,soybean floor, rye hull, rye meal, rye straw, rye flour, rice straw,rice hull, sorghum straw, sorghum hull, sunflower seeds, bamboo,lemongrass, switchgrass, catnip, oregano, parsley, rosemary, sage,thyme, valerian root, alyssum, chrysanthemum, honeysuckle, hops,lavender, apples, berries, orange peels, orange pulp, sunflower hulls,coffee, tea, sawdust, paper, cellulose, corncob, corn kernel, DistillersDried Grain (DDG), corn pellet, oaf pellet, barley pellet, wheatmiddlings, soybean pellet, rye pellet, rice grain, rice pellet, sorghumgrain, sorghum pellet, sunflower seed, almond, pistachio, walnut, pecan,hazelnut, peanut, acorn, wheat middlings, wheat straws, or combinationsthereof.

Another aspect of the present disclosure is a pet litter comprisingdried particles of compacted material comprising expanded perlite, thedried particles having a density of about 25 lb/ft³ to about 45 lb/ft³,preferably about 30 lb/ft³ to about 42 lb/ft³. Yet another aspect of thepresent disclosure is a pet litter made by any of the methods disclosedherein.

Another aspect of the present disclosure is a sealed package at leastpartially enclosing any of the embodiments of the pet litter disclosedherein, for example a sealed box or a sealed bag containing such petlitter. A further aspect of the present disclosure is a method of usinga pet litter, the method comprising positioning at least a portion of apet litter contained by a package into a litter box. The method canmanage animal waste, such as cat urine; prevent or treat cat out-of-boxelimination; or treat or prevent lower urinary tract diseases in a cat,such as urinary plugs, struvite or oxalite stones, idiopathic cystitis,or renal reflux. In an embodiment, one or more of the pet littersdisclosed herein are used to treat a cat having an out-of-boxelimination issue. As used herein, a cat that has “an out-of-boxelimination issue” is a cat that has eliminated outside of the litterbox at least once in the last month, and in an embodiment eliminatedoutside of the litter box at least once in the last week.

EXAMPLES

The following non-limiting examples are illustrative of embodiments ofthe pet litters provided by the present disclosure and advantagesthereof.

Example 1: Absorbent Granule Production—1

Absorbent granules were produced using a compaction process.

1. Expanded perlite fines, starch, and water were blended and then fedinto a set of compacting rolls (Table 1).

2. The compaction rolls, having roll back-pressure force set-point of1,300 psi, formed the in-feed into pellets.

3. The pellets were then crushed and sized to −8/+30 mesh.

4. The screened material was then dried to a moisture content of approx.2%.

5. After drying, the granular absorbent material was evaluated fordensity, absorption, and particle integrity (attrition).

TABLE 1 Litter Formulation (pre-dried) Ingredient Example 1 Example 2Example 3 Example 7 Swelling Clay — —  3.2% — (Bentonite) Non-SwellingClay —  7.9% — — Perlite Fines 76.3% 69.6% 74.3% 73.3% Starch  3.7% 2.5%  2.5% 3.6% Water 20.0% 20.0% 20.0% 20.0% Guar — — — 3.1%

Example 2: Absorbent Granule Production—2

Absorbent granules were produced using a compaction process.

1. Expanded perlite fines, starch, non-swelling calcium montmorilloniteclay, and water were blended and then fed into a set of compacting rolls(Table 1).

2. The compaction rolls, having roll back-pressure force set-point of1,300 psi, formed the in-feed into pellets.

3. The pellets were then crushed and sized to −8/+30 mesh.

4. The screened material was then dried to a moisture content of approx.2%.

5. After drying, the granular absorbent material was evaluated fordensity, absorption, and particle integrity (attrition).

Example 3: Absorbent Granule Production—3

Absorbent granules were produced using a compaction process.

1. Expanded perlite fines, starch, sodium bentonite, and water wereblended and then fed into a set of compacting rolls (Table 1).

2. The compaction rolls, having roll back-pressure force set-point of1,300 psi, formed the in-feed into pellets.

3. The pellets were then crushed and sized to −8/+30 mesh.

4. The screened material was then dried to a moisture content of approx.2%.

5. After drying, the granular absorbent material was evaluated fordensity, absorption, and particle integrity (attrition).

Example 4: Bulk Density Measurement

The bulk density of the absorbent granules from Example 1 was measuredusing a filling hopper (800 284-5779 Seedburo®; part number 151 FillingHopper complete with 64P Pan), stand, and pint sized (550.06 cm³ dryvolume) sample cup according to the procedure below:

1. The litter was poured into the filling hopper until it was full.

2. Next, the empty pint cup was placed on a balance and the balance waszeroed.

3. The cup was then placed beneath the filling hopper. The distancebetween the filling hopper discharge, and the top edge of the cup wasset at 2 inches.

4. The filling hopper discharge slide was then opened to allow productto fall into the empty sample cup. Litter was allowed to flow until thecup was full, and then for an additional 1 to 2 seconds of overflow.

5. A straight edge was then used to remove excess product from the topof the cup; leveling the cup contents with the rim of the cup.

6. The cup with litter was then returned to the balance and the weightof the litter recorded.

7. Steps 1-6 were repeated three times.

8. Mass value was converted to pounds per cubic foot (lb/ft³) using theconversion factor 1 gram per cubic centimeter (gm/cm³) equals 62.4269lb/ft³ (1 gram per dry pint (g/dry-pt) equals 0.113358 lb/ft³).

The average bulk density and standard deviation were calculated andreported in Table 2. As shown in Table 2, the tested pet litter wassignificantly less dense than the clay litter benchmarks.

Example 5: Absorption by Volume Measurement

The absorption by volume of the litter from Example 1 was measured usinga bulk density apparatus (800 284-5779 Seedburo®; part number 151Filling Hopper complete with 64P Pan); a straight-edge such as a 12 inchruler; a funnel; a ring support (4″) and support stand (24″); agraduated cylinder (at least 250 ml); an interval timer; and a specimencup with a known volume (150 ml) according to the procedure below.

1. A representative portion of sample was used to fill about ¾ of thehopper of the bulk density apparatus.

2. A tared specimen cup was placed under the center of the hopperapprox. 2¾ inches below the gate opening. The hopper gate was openedquickly and the sample allowed to fill the cup and overflow into the panbelow.

3. The sample was leveled to the top edge of the specimen cup using astraight edge and sawing motion. The volume of the sample was nowassumed to be equivalent to the volume of the specimen cup.

4. The sample was then transferred to the sorption funnel. The sorptionfunnel was positioned above the graduated cylinder using the ringsupport and stand so that the clamped hose end extended ½″ to 1″ intothe cylinder.

5. Using the graduated cylinder as a measure and transfer vessel, 250 mlof cold tap water (V_(initial)) was added to the sorption funnel.

6. After a 10 minute soak time, the 250 ml graduated cylinder was placedunder the funnel drain hose and the hose clamp released.

7. Water from the funnel was allowed to drain into the graduatedcylinder for 5 minutes.

8. Using fingers, the hose was squeezed to release any water trappedtherein.

9. The graduated cylinder was examined, and the total volume of waterdrained from the recorded (V_(final)).Volume of water absorbed (ml)=V _(initial) (initial water volume)−V_(final) (final water volume) % Absorption by volume=(Volume of waterabsorbed (ml)/Volume of specimen cup (ml))×100  Calculation ofPercentage Absorption by Volume:

Average values were recorded and are reported in Table 2. Referring toTable 2, absorption by volume of the tested pet litter is surprisinglygreater than that of both the non-clumping clay litter benchmark andintact granules of expanded perlite of the size −8/+30 mesh.

Example 6: Particle Integrity (Attrition) Measurement

The attrition of the absorbent material from Example 1 was measuredaccording to the procedure below:

1: A representative sample of between 150 mL and 300 mL was collectedand hand sieved on a 8″ diameter 30 mesh sieve. Any particles thatpassed through were discarded, and any that remained on the screen orstuck in the screen were brushed out and kept for further analysis.2. The sample was then poured into the bulk density hopper (Seedburo®;part number 151 Filling Hopper) and released into a tared ¼ cupmeasuring cup (60 mL). A straight edge was used to strike off the excessmaterial from the measuring cup.3. The tared measuring cup with the material was then placed on thescale to find the original mass of the sample, MO.4. The weighed sample was poured onto a 40 mesh sieve, and this screenplaced on top of a catch pan. The stack was then loaded into a Rotap(RX-29) and shaken with the arm engaged for 4 minutes.5. After shaking on the Rotap, the material in the pan was discarded,and the material on the screen and the material stuck in the 40 meshscreen were collected and weighed to find the final mass of the sample,MR.Attrition %=((MO−MR)/MO)×100   Calculation of Attrition %

The results of attrition testing were recorded and are reported in Table2. Referring to Table 2, the particle integrity of the tested pet litteris good (<1.0%).

Example 7: Clumping Litter Production

The material from Example 1 (using the 500 psi roll back-pressure) wascombined with a clumping agent (guar gum). This material was thenmeasured for clumping performance:

1. The litter base material (10 lbs) was added to a lab scale rotationalpan mixer (Mars Mineral DP-14).

2. The mixer was set to a low speed setting and guar gum (0.4 lbs) wasslowly added.

3. The finished material was then removed from the mixer.

Example 8: Clump Integrity Measurement

The material from Example 7 was tested for clump performance accordingto the following procedure:

1. An 8″ diameter sieve with ¾″ mesh was stacked on top of a sieve panand placed on the bottom of a support stand.

2. A trap door assembly was attached to the support stand and positionedten inches above ¾″ sieve.

3. A representative sample of the litter from Example 5 was added to alitter testing pan. The depth of material was three inches.

4. A self-leveling 25 ml burette was positioned on a support stand threeinches above the litter surface. This setup was used to dispense 25 mlaliquots of feline urine liquid to the litter surface, forming a clumpin the litter. This process was repeated in a variety of location of thelitter pan until the desired number of clumps was created (in this case20 clumps).5. At the end of the desired time interval (15 min or 24 hr), the clumpwas removed from the litter, and its mass recorded as W1.6. The clump was then centered on the trap door mechanism assembled instep 2.7. Next the lever was actuated to release the trap door, allowing theclump to fall onto the ¾″ test sieve.8. The clump was carefully removed from the screen in a manner whichallowed loose material to fall free of the clump, but not in a mannerwhich caused additional damage to the clump. If the clump broke intopieces, largest piece retained on the ¾″ screen was selected. If nothingis retained on the screen, the result is zero (0) weight.9. The clump or largest piece was weighed and the mass recorded as W2.10. The Percentage of Cohesion value was calculated using the followingformula:% Cohesion=(W2(final weight)/W1(initial weight))×100

The Percentage of Cohesion values for all clumps were averaged, and theresults recorded in Table 2. As shown in Table 2, the Percentage ofCohesion values for the tested pet litter were comparable to that of thecurrent clay litter.

TABLE 2 Summary of Testing Results Clump Clump Cohe- Cohe- Absorp- BulkAttri- sion: 15 sion: 24 Material tion by Density tion min. Hours ClassSample % Vol (lb/ft³) (%) (%) (%) Raw Expanded 40.6 4.2 2.5 — — MaterialPerlite Non-swelling 49.7 46.2 0.19 — — (Ca Montmo- rillonite) Clay Non-Example 1 69.2 33.3 0.96 — — clumping Example 2 66.4 41.2 0.25 — —Litter Example 3 68.4 41.9 0.25 — — Clumping Commercial — 55.3 0.19 93.098.2 Litter CL (CL) Example 6 — 33.3 0.96 96.5 97.2

CONCLUSIONS

The results show that the tested pet litter is a low density granularabsorbent with good particle integrity and has surprisingly improvedabsorption relative to traditional clay litter and the pre-processedprincipal raw material. Specifically, the density is reduced relative toboth clumping and non-clumping clay litters (Table 2), the particleintegrity is good (<1.0%), and the absorption by volume is surprisinglygreater than the non-clumping clay litter benchmark as well as intactgranules of expanded perlite of the size −8/+30 mesh (Table 2). Thetested absorbent material can be used to formulate a clumping petlitter, and demonstrates comparable clumping to that of the clay-basedclumping litter benchmark (Table 2).

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A method of making a pet littercomprising: compacting a material comprising expanded perlite fines toform a compacted material comprising expanded perlite fines, wherein thecompacting is performed at a pressure from about 500 to about 1,300 psi;breaking the compacted material comprising expanded perlite fines toform particles of the compacted material comprising expanded perlitefines; separating the particles which have a size within a predeterminedsize range from a remainder of the particles; drying the particles whichhave the size within the predetermined size range; and using the driedparticles as at least a portion of the pet litter, wherein the petlitter does not contain activated carbon.
 2. The method of claim 1,wherein the expanded perlite fines have a size not greater than about600 microns.
 3. The method of claim 1, wherein the material comprisingexpanded perlite fines comprises about 0.5 wt. % to about 5.0 wt. % of abinder.
 4. The method of claim 3, wherein the binder is selected fromthe group consisting of (i) a starch, (ii) a clay, and (iii) a starchand a clay.
 5. The method of claim 4, wherein at least a portion of thebinder is added to the expanded perlite fines as a dry mix before thecompacting of the material.
 6. The method of claim 4, wherein at least aportion of the binder is pre-blended with water and then added to theexpanded perlite fines before the compacting of the material.
 7. Themethod of claim 1, wherein the material comprising expanded perlitefines comprises about 15.0 wt. % to about 25.0 wt. % of water.
 8. Themethod of claim 1, wherein the material comprising expanded perlitefines comprises about 50 wt. % to about 85 wt. % of the expanded perlitefines.
 9. The method of claim 1, wherein the predetermined size range isabout 595 microns to about 2,380 microns.
 10. The method of claim 1,wherein the particles are dried to a moisture content of about 0.25 wt.% to about 10.0 wt. %.
 11. A pet litter made by the method of claim 1.